1. Field of the Invention
The present invention relates to a method and an apparatus for evaluation of an eddy current testing (or ECT) signal. More specifically, the invention relates to the method and apparatus useful when applied to flaw detection using an eddy current testing sensor on a multi-coil system, a rotation system, or a two-dimensional scanning system (hereinafter referred to as the multi-coil system or the like).
2. Description of Related Art
Eddy current testing is known as a method for nondestructive testing of a metal. This method involves generating an eddy current in a member to be measured, by a magnetic flux generated by a coil supplied with an exciting current, and obtaining an eddy current testing signal based on a magnetic flux generated by the eddy current as an output signal from the coil. The eddy current testing signal reflects the location, shape, depth, etc. of a flaw existing in the member to be measured. Based on this eddy current testing signal, the member to be measured, which is a metal (magnetic material), can be inspected nondestructively.
To test, for example, a heat exchange tube for a flaw by the eddy current testing method, a coil, which is an eddy current testing sensor, is inserted into the heat exchange tube to obtain an eddy current testing signal. Such a signal representing a flaw changes not only in amplitude, but also in phase. Thus, observation of the eddy current testing signal in one-dimension is not sufficient, and its two-dimensional observation is necessary. Hence, the eddy current testing of the heat exchange tube uses an eddy current testing apparatus which generates a two-dimensional output appearing along an X-axis and a Y-axis. An eddy current testing signal expressed on a voltage plane draws a Lissajous"" figure as shown in FIG. 7.
Such a Lissajous"" figure is characterized by its size and its slope relative to the X-axis. That is, the size of the Lissajous"" figure is proportional to the volume of the flaw, and its slope relative to the X-axis corresponds to the depth of the flaw. In the eddy current testing of a heat exchange tube, the depth of the flaw is important information. Thus, flaw detection is performed in a predetermined manner based on the phase of the eddy current testing signal. In detail, the phase angle of the eddy current testing signal (a value as a complex number) representing a flaw is measured. The measured phase angle is mapped on a characteristic curve (prepared beforehand) as shown in FIG. 8 which illustrates the relationship between the phase angle of an eddy current testing signal and the depth of a flaw. Based on a reading taken from the characteristic curve, the depth of the flaw is estimated.
As described above, eddy current testing according to the earlier technologies measures the phase angle of the eddy current testing signal, and maps the measured value on the prepared characteristic curve illustrating the relationship between the phase angle of the eddy current testing signal and the depth of the flaw to estimate the depth of the flaw. However, the phase angle and the depth of the flaw do not necessarily correlate exactly, and the accuracy of flaw detection may be practically insufficient. This is because, given the same depth of the flaw, the phase angle may vary according to various factors, such as the shape of the flaw (e.g., length, width) and the relative positional relationship between the flaw and the coil. Particularly in the case of an internal flaw (a flaw on an inner peripheral surface of a heat exchange tube) showing a low rate of change in the depth of flaw in comparison with the rate of change in the phase angle of the eddy current testing signal, the accuracy of flaw detection may often be problematical.
The present invention has been accomplished in light of the problems with earlier technologies. An object of the invention is to provide a method and an apparatus for evaluation of an eddy current testing signal, the method and apparatus being capable of improving accuracy in evaluating the depth of a flaw detected by eddy current testing, and increasing accuracy in evaluating the amount of a decrease in the wall thickness of a member to be measured, as well as accuracy in discerning a false signal.
To attain the above object, the invention is characterized by the following aspects:
1) A method for generating a feature amount from an eddy current testing signal, comprising:
generating the feature amount based on the eddy current testing signal obtained by measuring a member to be measured, the feature amount being a numerical expression of not only a phase angle of the eddy current testing signal highly correlated to a depth of a flaw, and an amplitude of the eddy current testing signal, but also a feature highly correlated to a secondary factor which is other than the depth of the flaw and which affects a waveform of the eddy current testing signal.
According to this aspect, signals around a peak of the eddy current testing signal can be incorporated into the feature amount. This makes it possible to quantify an influence which elements affecting the evaluation of an eddy current testing signal, i.e., elements becoming the cause of a noise when the depth of a flaw is evaluated by use of the phase angle and the amplitude alone, exert on the evaluation of the flaw depth. Consequently, this aspect of the invention can provide data for more accurate determination of the depth of a flaw on the basis of an eddy current testing signal.
2) A method for evaluation of an eddy current testing signal, comprising:
generating a feature amount based on a sample eddy current testing signal obtained by measuring a standard specimen as a member to be measured and of a known depth of a flaw, the feature amount being a numerical expression of not only a phase angle of the sample eddy current testing signal highly correlated to the depth of the flaw, and an amplitude of the sample eddy current testing signal, but also a feature highly correlated to a secondary factor which is other than the depth of the flaw and which affects a waveform of the sample eddy current testing signal;
generating an evaluation parameter by learning with use of the feature amount, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to known correct answer data as an amount expressing the depth of the flaw of the standard specimen;
generating a feature amount similar to that from the sample eddy current testing signal by use of an actual measurement eddy current testing signal obtained by eddy current testing of a member as an object to be measured; and
generating data representing the depth of the flaw on the basis of the feature amount based on the actual measurement eddy current testing signal, and the evaluation parameter corresponding to the feature amount.
According to this aspect, a feature amount as a numerical expression of features effective for evaluation of the depth of a flaw is statistically processed to generate a single evaluation parameter. The use of such a single evaluation parameter enables the depth of the flaw to be evaluated based on an actual measurement eddy current testing signal. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with a judgment of the depth of the flaw based only on the phase angle and amplitude of the actual measurement eddy current testing signal.
3) The method for evaluation of an eddy current testing signal as described in 2), comprising:
classifying a type of the flaw, such as an external flaw or an internal flaw, based on the sample eddy current testing signal, and generating a similar feature amount and a similar evaluation parameter according to the classified type; and
classifying a type of the flaw based on the actual measurement eddy current testing signal obtained by eddy current testing of the member to be measured, and performing generation of a feature amount according to the classified type, and generation of data representing the depth of the flaw based on the evaluation parameter according to the classified type.
According to this aspect, the method for evaluation described in 2) can be performed according to the type of a flaw. Consequently, this aspect of the invention can evaluate the depth of the flaw more accurately than the aspect of invention 2).
4) A method for evaluation of an eddy current testing signal, comprising:
generating feature amounts based on a plurality of sample eddy current testing signals obtained by measuring a standard specimen, as a member to be measured and with a known amount of decrease in wall thickness, by means of an eddy current testing sensor for obtaining data at many locations distributed in two-dimensions, such as a multi-coil system sensor having many coils, the feature amounts being numerical expressions of not only phase angles of the sample eddy current testing signals highly correlated to the amount of decrease in wall thickness, and amplitudes of the sample eddy current testing signals, but also a feature highly correlated to a secondary factor which is other than the amount of decrease in wall thickness and which affects waveforms of the sample eddy current testing signals;
sorting the feature amounts based on the sample eddy current testing signals according to predetermined standards, such as a sequence of phase, so that an efficiency of subsequent learning is improved;
generating an evaluation parameter by learning with use of the feature amounts, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to known correct answer data as an amount expressing the amount of decrease in the wall thickness of the standard specimen;
generating feature amounts similar to those from the sample eddy current testing signals by use of actual measurement eddy current testing signals obtained by eddy current testing of a member to be measured; and
generating data representing the amount of decrease in the wall thickness on the basis of the feature amounts based on the actual measurement eddy current testing signals, and the evaluation parameter corresponding to the feature amounts.
According to this aspect, feature amounts as numerical expressions of features effective for evaluation of the amount of decrease in wall thickness are statistically processed to generate a single evaluation parameter. The use of such an evaluation parameter enables the amount of decrease in wall thickness to be evaluated based on actual measurement eddy current testing signals. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with a judgment of the amount of decrease in wall thickness based only on the phase angles and amplitudes of the actual measurement eddy current testing signals.
5) A method for evaluation of an eddy current testing signal, comprising:
generating a feature amount based on a sample eddy current testing signal obtained by measuring a standard specimen as a member to be measured, which has a known flaw or has formed a pseudo-factor other than a flaw as a cause of a false eddy current testing signal, the feature amount being a numerical expression of not only a phase angle of the sample eddy current testing signal highly correlated to a flaw, and an amplitude of the sample eddy current testing signal, but also a feature highly correlated to a secondary factor which affects a waveform of the sample eddy current testing signal;
generating an evaluation parameter by learning with use of the feature amount, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to known correct answer data as a state signal representing the flaw or pseudo-factor of the standard specimen;
generating a feature amount similar to that from the sample eddy current testing signal by use of an actual measurement eddy current testing signal obtained by eddy current testing of a member to be measured; and
generating a state signal representing the flaw or the pseudo-factor on the basis of the feature amount based on the actual measurement eddy current testing signal, and the evaluation parameter corresponding to the feature amount.
According to this aspect, a feature amount as a numerical expression of features effective for evaluating whether the state under evaluation is a flaw or other pseudo-factor is statistically processed to generate a single evaluation parameter. The use of such an evaluation parameter makes it possible to evaluate whether the state under evaluation is a flaw or other pseudo-factor. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with judging, based only on the phase angle and amplitude, whether the state under evaluation is a flaw or other pseudo-factor.
6) An apparatus for evaluation of an eddy current testing signal, comprising:
feature amount generation means for receiving a sample eddy current testing signal obtained by measuring a standard specimen as a member to be measured and of a known depth of a flaw, and generating a feature amount being a numerical expression of not only a phase angle of the sample eddy current testing signal highly correlated to the depth of the flaw, and an amplitude of the sample eddy current testing signal, but also a feature highly correlated to a secondary factor which is other than the depth of the flaw and which affects a waveform of the sample eddy current testing signal;
correct answer data supply means for supplying known correct answer data as an amount expressing the depth of the flaw of the standard specimen;
learning means for receiving the feature amount and the correct answer data, and generating an evaluation parameter by learning with use of the feature amount, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to the correct answer data;
feature amount generation means for generating a feature amount similar to that from the sample eddy current testing signal by use of an actual measurement eddy current testing signal obtained by eddy current testing of a member as an object to be measured; and
evaluation results generation means for generating data representing the depth of the flaw on the basis of the feature amount based on the actual measurement eddy current testing signal, and the evaluation parameter corresponding to the feature amount.
According to this aspect, a feature amount as a numerical expression of features effective for evaluation of the depth of the flaw is statistically processed to generate a single evaluation parameter. The use of such an evaluation parameter enables the depth of the flaw to be evaluated based on an actual measurement eddy current testing signal. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with a judgment of the depth of the flaw based only on the phase angle and amplitude of the actual measurement eddy current testing signal.
It is difficult for a person to evaluate the depth of a flaw with the use of a feature element other than a phase angle. According to the above aspect, on the other hand, various feature elements other than a phase angle are statistically processed to generate an evaluation parameter. Hence, an eddy current testing signal can be judged globally, so that the accuracy of evaluation can be improved.
7) The apparatus for evaluation of an eddy current testing signal as described in 6), including:
classification means for classifying a type of flaw, such as an external flaw or an internal flaw, based on the actual measurement eddy current testing signal obtained by eddy current testing of the member to be measured;
evaluation parameter generation means adapted to classify the type of the flaw based on the sample eddy current testing signal, and generate the feature amount and the evaluation parameter according to the classified type;
the feature amount generation means for generating the feature amount based on the actual measurement eddy current testing signal being adapted to generate the feature amount according to a classification made by the classification means; and
the evaluation results generation means being adapted to generate the data representing the depth of the flaw on the basis of the feature amount and the evaluation parameter generated according to the classification.
According to this aspect, the method for evaluation described in 6) can be performed according to the type of a flaw. Consequently, this aspect of the invention can evaluate the depth of the flaw more accurately than the aspect of invention 6).
8) An apparatus for evaluation of an eddy current testing signal, comprising:
feature amount generation means for generating feature amounts based on a plurality of sample eddy current testing signals obtained by measuring a standard specimen, as a member to be measured and with a known amount of decrease in wall thickness, by means of an eddy current testing sensor for obtaining data at many locations distributed in two-dimensions, such as a multi-coil system sensor having many coils, the feature amounts being numerical expressions of not only phase angles of the sample eddy current testing signals highly correlated to the amount of decrease in wall thickness, and amplitudes of the sample eddy current testing signals, but also a feature highly correlated to a secondary factor which is other than the amount of decrease in wall thickness and which affects waveforms of the sample eddy current testing signals;
sorting means for sorting the feature amounts based on the sample eddy current testing signals according to predetermined standards, such as a sequence of phase, so that an efficiency of subsequent learning is improved;
correct data supply means for supplying known correct answer data as an amount expressing the amount of decrease in the wall thickness of the standard specimen;
learning means for receiving the feature amounts and the correct answer data, and generating an evaluation parameter by learning with use of the feature amounts, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to the correct answer data;
feature amount generation means for generating feature amounts similar to those from the sample eddy current testing signals by use of actual measurement eddy current testing signals obtained by eddy current testing of a member as an object to be measured; and
evaluation results generation means for generating data representing an amount of decrease in the wall thickness on the basis of the feature amounts based on the actual measurement eddy current testing signals, and the evaluation parameter corresponding to the feature amounts.
According to this aspect, feature amounts as numerical expressions of features effective for evaluating the amount of decrease in wall thickness are statistically processed to generate a single evaluation parameter. The use of such an evaluation parameter enables the amount of decrease in wall thickness to be evaluated based on actual measurement eddy current testing signals. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with a judgment of the amount of decrease in wall thickness based only on the phase angles and amplitudes of the actual measurement eddy current testing signals.
It is difficult for a person to evaluate the amount of decrease in wall thickness with the use of a feature element other than a phase angle. According to this aspect of the invention, on the other hand, various feature elements other than a phase angle are statistically processed to generate an evaluation parameter. Hence, an eddy current testing signal can be judged globally, so that the accuracy of evaluation can be improved.
9) An apparatus for evaluation of an eddy current testing signal, comprising:
feature amount generation means for generating a feature amount based on a sample eddy current testing signal obtained by measuring a standard specimen as a member to be measured, which has a known flaw or has formed a pseudo-factor other than a flaw as a cause of a false eddy current testing signal, the feature amount being a numerical expression of not only a phase angle of the sample eddy current testing signal highly correlated to a flaw, and an amplitude of the sample eddy current testing signal, but also a feature highly correlated to a secondary factor which affects a waveform of the sample eddy current testing signal;
correct data supply means for supplying known correct answer data as a state signal generated responsive to and expressing the flaw or pseudo-factor of the standard specimen;
learning means for receiving the feature amount and the correct answer data, and generating an evaluation parameter by learning with use of the feature amount, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to the correct answer data;
feature amount generation means for generating a feature amount similar to that from the sample eddy current testing signal by use of an actual measurement eddy current testing signal obtained by eddy current testing of a member as an object to be measured; and
evaluation results generation means for generating a state signal representing a flaw or a pseudo-factor on the basis of the feature amount based on the actual measurement eddy current testing signal, and the evaluation parameter corresponding to the feature amount.
According to this aspect, a feature amount as a numerical expression of features effective for evaluating whether the state under evaluation is a flaw or other pseudo-factor is statistically processed to generate a single evaluation parameter. The use of such an evaluation parameter, makes it possible to evaluate whether the state under evaluation is a flaw or other pseudo-factor. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with judging, based only on the phase angle and amplitude, whether the state under evaluation is a flaw or other pseudo-factor.
It is difficult for a person to evaluate, with the use of a feature element other than a phase angle, whether the state under evaluation is a flaw or other pseudo-factor. According to the above aspect of the invention, on the other hand, various feature elements other than a phase angle are statistically processed to generate an evaluation parameter. Hence, an eddy current testing signal can be judged globally, so that the accuracy of evaluation can be improved.
10) A method for evaluation of an eddy current testing signal, comprising:
generating a feature amount based on a sample eddy current testing signal obtained by measuring a standard specimen as a member to be measured and of a known depth of a flaw, the feature amount being a numerical expression of not only a phase angle of the sample eddy current testing signal highly correlated to the depth of the flaw, and an amplitude of the sample eddy current testing signal, but also a feature highly correlated to a secondary factor which is other than the depth of the flaw and which affects a waveform of the sample eddy current testing signal;
generating an evaluation parameter by learning with use of the feature amount, the evaluation parameter being a parameter for leading to known correct answer data as an amount expressing the depth of the flaw of the standard specimen;
repeating operations for generation of the feature amount based on the sample eddy current testing signal and generation of the evaluation parameter, with a combination of elements of the feature amount being changed, to generate a plurality of evaluation parameters;
generating a plurality of feature amounts similar to those from the sample eddy current testing signals for different combinations of elements of the feature amount by use of actual measurement eddy current testing signals obtained by eddy current testing of a member as an object to be measured;
generating data representing the depths of the flaw for the respective evaluation parameters on the basis of the respective feature amounts based on the actual measurement eddy current testing signals, and the respective evaluation parameters corresponding to the respective feature amounts; and
comparing the respective data representing the depths of the flaw, and when the depths of the flaw represented by the respective data fall within a predetermined range, adopting the depth of the flaw based on the predetermined range as an estimated value.
According to this aspect, a plurality of feature amounts as numerical expressions of features effective for evaluation of the depth of the flaw are statistically processed to generate a plurality of evaluation parameters. The use of such evaluation parameters enables the depth of the flaw to be evaluated based on an actual measurement eddy current testing signal. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with a judgment of the depth of the flaw based only on the phase angle and amplitude of the actual measurement eddy current testing signal. Since the plural feature amounts and evaluation parameters are used, moreover, more accurate evaluation than with the use of a single feature amount and a single evaluation parameter can be made.
11) The method for evaluation of an eddy current testing signal as described in 10), comprising:
classifying a type of the flaw, such as an external flaw or an internal flaw, based on the sample eddy current testing signal, and performing similar generation of feature amounts and evaluation parameters according to the classified type; and
classifying a type of the flaw based on the actual measurement eddy current testing signal obtained by eddy current testing of the member to be measured, and performing generation of the feature amounts according to the classified type and generation of the data representing the depth of the flaw based on the feature amounts and evaluation parameters according to the classified type.
According to this aspect, the method for evaluation described in 10) can be performed according to the type of a flaw. Consequently, this aspect of the invention can evaluate the depth of the flaw more accurately than the aspect of invention 10). Since the plurality of feature amounts and evaluation parameters are used, moreover, it is possible to make more accurate evaluation than with the use of a single feature amount and a single evaluation parameter.
12) A method for evaluation of an eddy current testing signal, comprising:
generating feature amounts based on a plurality of sample eddy current testing signals obtained by measuring a standard specimen, as a member to be measured and with a known amount of decrease in wall thickness, by means of an eddy current testing sensor for obtaining data at many locations distributed in two-dimensions, such as a multi-coil system sensor having many coils, the feature amounts being numerical expressions of not only phase angles of the sample eddy current testing signals highly correlated to the amount of decrease in wall thickness, and amplitudes of the sample eddy current testing signals, but also a feature highly correlated to a secondary factor which is other than the amount of decrease in wall thickness and which affects waveforms of the sample eddy current testing signals;
sorting the feature amounts based on the sample eddy current testing signals according to predetermined standards, such as a sequence of phase, so that an efficiency of subsequent learning is improved;
generating an evaluation parameter by learning with use of the feature amounts, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to known correct answer data as an amount expressing the amount of decrease in the wall thickness of the standard specimen;
repeating operations for generation of the feature amounts based on the sample eddy current testing signals, sorting, and generation of the evaluation parameter, while changing a combination of elements of the feature amount and the standards for sorting, to generate a plurality of evaluation parameters;
generating a plurality of feature amounts similar to those from the sample eddy current testing signals for different combinations of elements of the feature amount by use of actual measurement eddy current testing signals obtained by eddy current testing of a member as an object to be measured;
generating data representing the amounts of decrease in the wall thickness for the respective evaluation parameters on the basis of the respective feature amounts based on the actual measurement eddy current testing signals, and the respective evaluation parameters corresponding to the respective feature amounts; and
comparing the respective data representing the amounts of decrease in the wall thickness, and when the amounts of decrease in the wall thickness represented by the respective data fall within a predetermined range, adopting the amount of decrease in the wall thickness based on the predetermined range as an estimated value.
According to this aspect, a plurality of feature amounts as numerical expressions of features effective for evaluating the amount of decrease in wall thickness are statistically processed to generate a plurality of evaluation parameters. The use of such evaluation parameters enables the amount of decrease in wall thickness to be evaluated based on actual measurement eddy current testing signals. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with a judgment of the amount of decrease in wall thickness based only on the phase angles and amplitudes of the actual measurement eddy current testing signals. Since the plural feature amounts and evaluation parameters are used, moreover, more accurate evaluation than by use of a single feature amount and a single evaluation parameter can be made.
13) A method for evaluation of an eddy current testing signal, comprising:
generating a feature amount based on a sample eddy current testing signal obtained by measuring a standard specimen as a member to be measured, which has a known flaw or has formed a pseudo-factor other than a flaw as a cause of a false eddy current testing signal, the feature amount being a numerical expression of not only a phase angle of the sample eddy current testing signal highly correlated to a flaw, and an amplitude of the sample eddy current testing signal, but also a feature highly correlated to a secondary factor which affects a waveform of the sample eddy current testing signal;
generating an evaluation parameter by learning with use of the feature amount, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to known correct answer data as a state signal representing the flaw or pseudo-factor of the standard specimen;
repeating operations for generation of the feature amount based on the sample eddy current testing signal, and generation of the evaluation parameter, while changing a combination of elements of the feature amount, to generate a plurality of evaluation parameters;
generating a plurality of feature amounts similar to those from the sample eddy current testing signal for different combinations of elements of the feature amount by use of an actual measurement eddy current testing signal obtained by eddy current testing of a member to be measured;
generating state signals representing a flaw or a pseudo-factor for the respective evaluation parameters on the basis of the respective feature amounts based on the actual measurement eddy current testing signal, and the respective evaluation parameters corresponding to the respective feature amounts; and
comparing the respective state signals to discern, based on coincidence of contents of the state signals, whether the actual measurement eddy current testing signal is a signal representing a flaw, or a false signal.
According to this aspect, plural feature amounts as numerical expressions of features effective for evaluating whether the state under evaluation is a flaw or other pseudo-factor are statistically processed to generate plural evaluation parameters. The use of such evaluation parameters makes it possible to evaluate whether the state under evaluation is a flaw or other pseudo-factor. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with judging, based only on the phase angle and amplitude, whether the state under evaluation is a flaw or other pseudo-factor. Since the plural feature amounts and evaluation parameters are used, moreover, more accurate evaluation than when using a single feature amount and a single evaluation parameter can be made.
14) An apparatus for evaluation of an eddy current testing signal, comprising:
feature amount generation means for receiving a sample eddy current testing signal obtained by measuring a standard specimen as a member to be measured and of a known depth of a flaw, and generating a feature amount being a numerical expression of not only a phase angle of the sample eddy current testing signal highly correlated to the depth of the flaw, and an amplitude of the sample eddy current testing signal, but also a feature highly correlated to a secondary factor which is other than the depth of the flaw and which affects a waveform of the sample eddy current testing signal:
correct answer data supply means for supplying known correct answer data as an amount expressing the depth of the flaw of the standard specimen;
learning means for receiving the feature amount and the correct answer data, and generating an evaluation parameter by learning with use of the feature amount, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to the correct answer data;
evaluation parameter generation means for repeating operations for generation of the feature amount based on the sample eddy current testing signal and generation of the evaluation parameter, with a combination of elements of the feature amount being changed, to generate a plurality of evaluation parameters;
feature amount generation means for generating a plurality of feature amounts similar to those from the sample eddy current testing signal for different combinations of elements of the feature amount by use of an actual measurement eddy current testing signal obtained by eddy current testing of a member as an object to be measured;
evaluation results generation means for generating data representing depths of a flaw for the respective evaluation parameters on the basis of the respective feature amounts based on the actual measurement eddy current testing signal, and the respective evaluation parameters corresponding to the respective feature amounts; and
verification means for comparing the respective data representing the depths of the flaw which have been obtained as output signals from the evaluation results generation means, and when the depths of the flaw represented by the respective data fall within a predetermined range, adopting the depth of the flaw based on the predetermined range as an estimated value.
According to this aspect, plural feature amounts as numerical expressions of features effective for evaluation of the depth of the flaw are statistically processed to generate plural evaluation parameters. The use of such evaluation parameters enables the depth of the flaw to be evaluated based on an actual measurement eddy current testing signal. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with a judgment of the depth of the flaw based only on the phase angle and amplitude of the actual measurement eddy current testing signal.
It is difficult for a person to evaluate the depth of a flaw with the concomitant use of a feature element other than a phase angle. According to this aspect of the invention, on the other hand, various feature elements other than a phase angle are statistically processed to generate an evaluation parameter. Hence, an eddy current testing signal can be judged globally, so that the accuracy of evaluation can be improved. Since the plural feature amounts and evaluation parameters are used, moreover, more accurate evaluation than when using a single feature amount and a single evaluation parameter can be made.
15) The apparatus for evaluation of an eddy current testing signal as described in 14), including:
classification means for classifying a type of flaw, such as an external flaw or an internal flaw, based on the actual measurement eddy current testing signal obtained by eddy current testing of the member to be measured;
the evaluation parameter generation means being adapted to classify the type of the flaw based on the sample eddy current testing signal, and generate the feature amount and the evaluation parameter according to the classified type;
the feature amount generation means for generating the feature amount based on the actual measurement eddy current testing signal being adapted to generate the feature amount according to a classification made by the classification means; and
the evaluation results generation means being adapted to generate the data representing the depth of the flaw on the basis of the feature amount and the evaluation parameter generated according to the classification.
According to this aspect, the method for evaluation described in 14) can be performed according to the type of a flaw. Consequently, this aspect of the invention can evaluate the depth of the flaw more accurately than the aspect of invention 14). Since the plural feature amounts and evaluation parameters are used, moreover, more accurate evaluation than with the use of a single feature amount and a single evaluation parameter can be made.
16) An apparatus for evaluation of an eddy current testing signal, comprising:
feature amount generation means for generating feature amounts based on a plurality of sample eddy current testing signals obtained by measuring a standard specimen, as a member to be measured and with a known amount of decrease in wall thickness, by means of an eddy current testing sensor for obtaining data at many locations distributed in two-dimensions, such as a multi-coil system sensor having many coils, the feature amounts being numerical expressions of not only phase angles of the sample eddy current testing signals highly correlated to the amount of decrease in wall thickness, and amplitudes of the sample eddy current testing signals, but also a feature highly correlated to a secondary factor which is other than the amount of decrease in wall thickness and which affects waveforms of the sample eddy current testing signals;
sorting means for sorting the feature amounts based on the sample eddy current testing signals according to predetermined standards, such as a sequence of phase, so that an efficiency of subsequent learning is improved;
correct data supply means for supplying known correct answer data as an amount expressing the amount of decrease in the wall thickness of the standard specimen;
learning means for receiving the feature amounts and the correct answer data, and generating an evaluation parameter by learning with use of the feature amounts, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to the correct answer data;
evaluation parameter generation means for repeating operations for generation of the feature amounts based on the sample eddy current testing signals, sorting, and generation of the evaluation parameter, while changing a combination of elements of the feature amount and the standards for sorting, to generate a plurality of evaluation parameters;
feature amount generation means for generating a plurality of feature amounts similar to those from the sample eddy current testing signals for different combinations of elements of the feature amount by use of actual measurement eddy current testing signals obtained by eddy current testing of a member as an object to be measured;
evaluation results generation means for generating data representing the amounts of decrease in the wall thickness for the respective evaluation parameters on the basis of the respective feature amounts based on the actual measurement eddy current testing signals, and the respective evaluation parameters corresponding to the respective feature amounts; and
verification means for comparing the respective data representing the amounts of decrease in the wall thickness which have been obtained as output signals from the evaluation results generation means, and when the amounts of decrease in the wall thickness represented by the respective data fall within a predetermined range, adopting the amount of decrease in the wall thickness based on the predetermined range as an estimated value.
According to this aspect, plural feature amounts as numerical expressions of features effective for evaluating the amount of decrease in wall thickness are statistically processed to generate plural evaluation parameters. The use of such evaluation parameters enables the amount of decrease in wall thickness to be evaluated based on actual measurement eddy current testing signals. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with a judgment of the amount of decrease in wall thickness based only on the phase angles and amplitudes of the actual measurement eddy current testing signals.
In making evaluation, a person finds difficulty in evaluating the amount of decrease in wall thickness with the concomitant use of a feature element other than a phase angle. According to the above aspect of the invention, on the other hand, various feature elements other than a phase angle are statistically processed to generate an evaluation parameter. Hence, an eddy current testing signal can be judged globally, so that the accuracy of evaluation can be improved. Since the plural feature amounts and evaluation parameters are used, moreover, more accurate evaluation than with the use of a single feature amount and a single evaluation parameter can be made.
17) An apparatus for evaluation of an eddy current testing signal, comprising:
feature amount generation means for generating a feature amount based on a sample eddy current testing signal obtained by measuring a standard specimen as a member to be measured, which has a known flaw or has formed a pseudo-factor other than a flaw as a cause of a false eddy current testing signal, the feature amount being a numerical expression of not only a phase angle of the sample eddy current testing signal highly correlated to a flaw, and an amplitude of the sample eddy current testing signal, but also a feature highly correlated to a secondary factor which affects a waveform of the sample eddy current testing signal;
correct data supply means for supplying known correct answer data as a state signal generated responsive to and representing the flaw or pseudo-factor of the standard specimen;
learning means for receiving the feature amount and the correct answer data, and generating an evaluation parameter by learning with use of the feature amount, the evaluation parameter being a parameter for outputting a value with a sufficiently small error relative to the correct answer data;
evaluation parameter generation means for repeating operations for generation of the feature amount based on the sample eddy current testing signal and generation of the evaluation parameter, while changing a combination of elements of the feature amount, to generate a plurality of evaluation parameters;
feature amount generation means for generating a plurality of feature amounts similar to those from the sample eddy current testing signal for different combinations of elements of the feature amount by use of an actual measurement eddy current testing signal obtained by eddy current testing of a member as an object to be measured;
evaluation results generation means for generating state signals representing a flaw or a pseudo-factor for the respective evaluation parameters on the basis of the respective feature amounts based on the actual measurement eddy current testing signal, and the respective evaluation parameters corresponding to the respective feature amounts; and
verification means for comparing the respective state signals which have been obtained as output signals from the evaluation results generation means, and when states represented by the respective state signals are consistent, identifying the states to be a flaw or a pseudo-factor.
According to this aspect, plural feature amounts as numerical expressions of features effective for evaluating whether the state under evaluation is a flaw or other pseudo-factor are statistically processed to generate plural evaluation parameters. The use of such evaluation parameters makes it possible to evaluate whether the state under evaluation is a flaw or other pseudo-factor. Consequently, this aspect of the invention can markedly improve accuracy of evaluation in comparison with judging, based only on the phase angle and amplitude, whether the state under evaluation is a flaw or other pseudo-factor.
In evaluating whether the state under evaluation is a flaw or other pseudo-factor, a person finds it difficult to make evaluation with the concomitant use of a feature element other than a phase angle. According to the above aspect of the invention, on the other hand, various feature elements other than a phase angle are statistically processed to generate an evaluation parameter. Hence, an eddy current testing signal can be judged globally, so that the accuracy of evaluation can be improved. Since the plural feature amounts and evaluation parameters are used, moreover, more accurate evaluation than when using a single feature amount and a single evaluation parameter can be performed.